Rectangular and saw-tooth impulse generator



1951 A. A. VARELA RECTANGULAR AND SAW-TOGTH IMPULSE GENERATOR 3 Sheets-Sheet 1 Filed June 19, 1942 Dec. 25, 1951 VARELA 2,579,525

RECTANGULAR AND SAW-TOOTH IMPULSE GENERATOR Filed June 19, 1942 3 Sheets-Sheet 2 Ywe/wto'a ArthurA. Varela Dec. 25, 1951 A. A. VARELA 2,579,525

RECTANGULAR AND SAW-TOOTH IMPULSE GENERATOR Filed June 19, 1942 3 Sheets-Sheet 3 3 W1) Q/WbO b ArthurA. Varela Patented fies. 25, 1951 RECTANGULAR AND SAW-TOOTH IMPULSE GENERATOR Arthur A. Varela, Washington, D. 0.

Application June 19, 1942, Serial No. 447,671

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 30 Claims.

This invention relates to electrical impulse generators and more particularly to circuits capable of generating electrical impulses having rectangular and saw-tooth wave forms.

There has long been a need in the art for means, of simple design and construction, capable of generating high voltage electrical impulses of rectangular or saw-tooth wave forms with a high degree of stability and efficiency, with such means so characterized that the impulses are of constant duration and are generated at an extremely high rate of speed so that the same may be utilized for controlling operation of various electrical machines, especially devices operating on ultra high frequencies.

The principal object of the present invention is to provide the foregoing means.

Another object is to provide a novel circuit arrangement for discharging a potential storing device at a constant rate for a predetermined period of time.

Another object is to provide novel means for periodically discharging a condenser through a discharge circuit at a constant rate in accordance with a preselected synchronizing source whereby flow of constant current is maintained in the discharge circuit for a predetermined period of time in a periodic manner determined by the synchronizing source.

Another object is to provide an impulse generator for producing electrical impulses of rectangular and saw-tooth wave forms including a condenser which is periodically discharged through a discharge circuit including an impedance having a definite relation with the capacity of said condenser and so characterized that a substantially linearly varying voltage is generated across the impedance for a predetermined period of time following the instant the condenser discharge commences and so that constant current flows through the discharge circuit for such predetermined period of time.

Another object is to provide an impulse generator having the foregoing characteristics wherein the impedance means comprises a filter network having a plurality of capacitance and inductance combinations, with each combination tuned to a diiierent frequency and serially connected in harmonic relationship, and with the value of capacitances having a definite relationship to the value of the condenser.

Another object is to provide an electrical impulse generator having a plurality of condensers that are charged in parallel relation with a source of potential including novel means for to provide novel means for applying a transient linear sweep on the cathode ray oscillograph.

Still another object is to provide novel means for anode keying of ultra high frequency oscillator circuits.

Still another object is to provide a novel electrical arrangement for periodically supplying electrical energy of constant values, of a predetermined duration, to the electrical and magnetic fields of a magnetron employed in ultra high frequency oscillator circuits whereby impulse operation of such circuits is obtained.

Other objects and features of the invention will appear more fully from the following detailed description when considered together with the accompanying drawings which disclose several embodiments of the invention. It is to be eX- pressly understood, however, that the drawings are designed for purposes of illustration only and not as a definition of the limits of the invention, reference for the latter purpose being had to the appended claims.

In the drawings, wherein similar reference characters denote similar parts throughout the several views:

Fig. l is a diagrammatic showing of an electrical impulse generator embodying the principles of the present invention;

Fig. 2 is a schematic illustration of a sawtooth voltage wave form produced by the generator disclosed in Fig. 1;

Fig. 3 is a schematic illustration of a rectangular voltage wave form produced by the generator disclosed in Fig. l

Fig. 4 is a showing of a further application of the impulse generator disclosed in Fig. 1;

Fig. 5 is a diagrammatic illustration of a further embodiment of the present invention, and

Fig. 6 is a diagrammatic showing of a still further embodiment of the invention.

With reference more particularly to Fig. l of the drawings, and electrical impulse generator embodying the principles of the present invention is disclosed therein including a potential storing device, such as a capacitance H). A

source of potential from terminals ii and i2.

is applied to the high and low potential terminals of capacitance iii, respectively, with impedance l3 and choke coil Hi included in the high potential connection, to charge the capacitance. The generator further includes a discharge circuit comprising inductance ld, filter network l6 and a resistance i'i, connected in series between the high and low potential terminals of capacitance Ii]. In order to control discharge of the capacitance through such discharge circuit a gaseous electron discharge device lEl is connected between the high potential terminal of the capacitance and inductance 55. More particularly, device [8 comprises a conventional triode gas tube having a plate l9, a filament 2d and a control electrode 2!. Plate I9 is connected to the high potential terminal of capacitance ill, while filament 25 is connected to inductance i5, and to the low potential terminal of the capacitance, or ground potential, through choke coils 22 and 23 and the secondary winding of transformer 25. The heater voltage for filament 26 is applied thereto in a conventional manner through transformer a. Control electrode 25 is connected to the low potential terminal of bias supply '25, through choke coil 23 and impedance 2'1 to normally maintain the control electrode negatively biased and de vice E8 in a de-ionized condition. Control electrode 2E is also connected to a synchronizing source at point 28, through capacitance 29. When the bias on control electrode 2i is increased above the cut-off potential of device I8, upon application of a positive potential at point 28, device It is ionized to'form an electrical connection between the high potential terminal of capacitance Hi and inductance l whereby the capacitance discharges serially through inductance Iii, filter-network i6 and resistance ii to ground potential. The time constants of choke coils 22 and 23 are of such duration to prevent discharge of capacitance it therethrough, for a predetermined period of time following the instant device is ionized, as will appear more fully hereinafter. The synchronizing source applied to point 28 for controlling the discharge of capacitance it may comprise equally spaced positive impulses, or any form of alternating current capable of periodically ionizing device it at a desired rate.

Filter network l6 includes a plurality of serially connected filter sections 30, 35, 32, 33 and 3d. Each of the filter sections include a capacitance 35, of equal capacity, and an inductance, of different values, connected in parallel with the capacitance so that each filter section 36, 3!, 32, 33 and 3dresonates at a different frequency. Filter section 36 includes inductance 35 of a predetermined value to tune the filter section at a certain frequency which may be considered the fundamental frequency since the duration of the rectangular and saw-tooth impulses produced by the generator is determined thereby, while inductances 31, 38, 39 and %9 respectively included in filter sections 3i, 3 33 and 3d, are of predetermined values to tune each of the filter sections to frequencies equal to a certain harmonic of the frequency of filter section 39, or of the fundamental frequency. Filter section 3| is tuned to a frequency equal to the first harmonic of the fundamental frequency, while filter sections 32, 33 and 34 are respectively tuned to frequencies equal to the second, third and nth harmonic of the fundamental frequency. In order to obtain a series harmonic filter having the foregoing characteristics the values of inductances 3?, 3S, and Mi are inversely proportional to the square of the harmonic number of the filter sections in which each inductance is included. The characteristic impedance value of each filter section is therefore inversely proportional to the harmonic of the fundamental frequency to which each filter is tuned. The transient impedance value of filter network: It, that is, the impedance value of the network for a predetermined period of time following the instant a source of current flows therethrough, thus varies as a linear function of time for a predetermined period of time determined by the fundamental frequency of the filter network, which in the present instance, is the resonant frequency of filter section 26.

When current flows through a filter network having the foregoing characteristics a voltage is generated across the network that varies as a-substantially linear function for a predetermined period of time, since the transient impedance of the filter network offers an opposition to current flow therethrough that varies substantially as a linear function of time for such predetermined period of time following the instant current initially flows therethrough. As mentioned heretofore, the fundamental frequency of the filter network determines the period of time following the initial fiow of current therethrough during which a substantiallylinear voltage is generated across the filter. Such period of time is equal to 21.- /LiC1, wherein L1 and C1 correspond respectively to the values of inductance 355 and'capacitance 35 of filter section 39. The foregoing may be more readily understood with reference to Fig. 2 of the drawings wherein the voltage generated across filter network It as well as the voltages generated in the filter sections during the time interval 21r\/L1C1 are shown. At the instant current initially flows through the filter network generation of sinusoidal voltages is initiated in sections 39, 3!, 32, 33 and 34. Such sinusoidal voltages are of predetermined frequencies determined by the capacitance and inductance of each filter section. More particularly, the sinusoidal voltage generated across filter section 39 is at a frequency corresponding to the fundamental frequency of the filter network and a complete sinusoidal cycle is generated during the time interval 21r /L1C1. Also, the sinusoidal voltages appearing across filter sections 3!, 32, 33 and 34 are at frequencies corresponding to certain harmonics of the fundamental frequency, for reasons mentioned heretofore, and such sinusoidal oscillations continue in each of the latter filter sections for a period of time equal to 21r\/L1C1. Since the characteristic impedance value of each filter section is inversely proportional to the harmonic number to which each is tuned, the amplitudes of the sinusoidal voltages generated across each sectionare inversely proportional to the harmonic numbers thereof. As shown in Fig. 2, the sinusoidal voltage generated across filter section 3c is expressed by the function A1 sin wit, wherein A1 represents the voltage across the section, and wit the frequency at which the section is tuned. Since filter section 30 is tuned to a frequency corresponding to the first harmonic of the fundamental frequency, and furthermore since the characteristic impedance of the filter sections is inversely proportional to the harmonic number of the fundamental frequency towhich the sec- 5' tions are tuned, the voltage generated across filter section 3| is expressed as Moreover, since the voltage generated across filter section 32 is expressed as Sin 2L01t total l Sill i -F 3 Sin 2w t+ A sin 3w t+ sin we t The foregoing expression is a Fourier series for a saw-tooth wave form. With an infinite number of serially connected filter sections having the proper harmonic relationship therebetween, the total voltage generated across such a filter produces a perfect saw-tooth wave form, as shown in Fig. 2. Since a large number of filter sections is required in order to obtain a perfect saw toothwave form, inductance I5 is connected in series with filter network I6 so that a substantially linear voltage is generated across the filter network without necessitating employment of an impracticable number of filter sections.

As mentioned heretofore, one of the objects of the present invention is to provide an electrical apparatus including a condenser so char acterized that the condenser is discharged at.

a constant rate, for a predetermined period of time following the instant the condenser is initially discharged, whereby a constant flow of current is maintained for such predetermined period of time. It has been found that in order to discharge capacitance Ill through inductance I5, filter network It and resistance IT, at a constant rate, the value of capacitance It) must have a definite relationship with the value of capacitances 35 of filter network I6. Since the charge on capacitance I5 is equal to the capacity of the capacitance times the voltage impressed thereon, the rate of change of the charge, or the discharge current, is equal to If the capacitance It) is discharged at a constant rate, namely, by constant current, then must necessarily equal a constant value. q= V,

Since also equals such a constant value and, therefore equals as a function of the rate of change of voltage 6. across the filter network. The rate of change of the voltage across filter I6 is equal to V X -I-R) 2+R 2ZV wherein V is the voltage applied to capacitance I0, R the resistance of the discharge circuit, Z the characteristic impedance of filter network I6 and T the time constant of the filter network. Therefore,

2+R 2ZV Since T equals 21r\/L1C1, the value of C may be expressed as VL C' 2 22 and furthermore, since grill/ l It is to be expressly understood therefore, that capacitances 35 have capacity values equal to one-half the capacity of capacitance I0. With the foregoing arrangement, capacitance Ill discharges at a constant rate for the period of time 21r /L 1E 1 following the instant the capacitance initially discharges, and therefore, a constant current is maintained in the dis-charge circuit comprising conductance I5, filter network I6 and resistance I? for the period 21r\/L1Ci following the instantcapacitance I0 is discharged upon operation of device I8.

Since a substantially constant current is maintained in the discharge circuit for a predetermined period of time following each instant that capacitance I0 is discharged therethrough, a substantially constant voltage is maintained across resistance IT for a period of time equal to 2m/L1C1. Such rectangular voltage form is shown in Fig. 3. It is to be expressly understood, that the saw-tooth voltage form generated across filter I5 and the rectangular voltage form maintained across impedance H, are generated simultaneously and are of equal duration. The foregoing may be more readily understood with simultaneous reference to Figs. 2 and 3. As will appear more fully hereinafter, resistance Il may comprise any electrical device to which periodic application of constant current is desired, such as a high frequency oscillator circuit for example.

In operation of the electrical impulse generator disclosed in Fig. 1, a source of direct current potential is applied across capacitance I!) from terminals II and I2 through impedance I3 and choke coil !4 to charge the capacitance. A synchronizing source, such as a series of equally spaced positive impulses, is applied to control electrode H, of device I8, for periodically ionizing the latter, to periodically dis charge capacitance ID through serially connected inductance I5, filter network I6 and resistance I I. Impedance I3 and choke coil I 4 are so selected that application of constant potential from terminals I I and I2 to capacitance I 0 is delayed for a period of time equal to 2TI"\/L1C1 following each instant the capacitances discharged. Capacitances 35 of filter network '7 f3: have a value equal to one-half the value. of capacitance Ill in order to maintain the discharge of capacitance ill at constant rate, as pointed out heretofore. Since capacitance l discharges at a constant rate for a period of time in /Z1751 following each instant device i8 is ionized, constant current flows through inductance I5 and filter network It for the period '21r '/L1C1. As mentioned heretofore, filter network "5 is the flow of current therethrough that varies as a substantially linear function o f time, for a period of time equal to 21r /L1C1, following the instant current initially fiows therethrough. Therefore, a voltage is generated across filter l6 that varies as asubstantially linear function of time for the period 21r /L1C1, following the instant capacitance it isdischarged, as shown in Fig. 2. Also, since constant current flows through resistance H for the period of time 21r\/L1C1, a substantially constant potential is maintained across the resistance during such period of time, as shown in Fig. 3. After lapse of the time interval 21n/L1C1, the voltage across filter network it, and across resistance ll, abruptly diminishes to zero and device I8 is thus abruptly deionized to terminate the discharge of capacitance It. In this regard, the time constants of choke coils 22 and 23 3 much greater than the time interval 21r\/L1C1 so that dis-charge of capacitance it there through is prevented during the time when device (8 is in an ionized state. Inductance I5, as mentioned above, functions to maintain the discharge current substantially constant withoututilizing an impracticable number of harmonic filter sections in filter network It. The electrical impulses generated by the apparatus disclosed in Fig. 1 are of a substantially sawtooth and rectangular wave form and may be employed separately 01' simultaneously for controlling operation of various electrical devices as will appear more fully hereinafter.

In Fig. 4 of the drawings the impulse generator described. heretofore is shown interconnected with an electrical device whereby indications of irregular transient voltages are obtained. The indicating device is shown as a cathode ray oscillograph including cathode 5| and anode, 52

for generating an electron beam, a control electrode 53 for controlling the intensity of the electron stream, and a pair of deflection plates 54 and 55'for controlling the deflection of the electron beam. The saw-tooth and rectangular voltage wave forms produced by the impulse generator described heretofore are fed to certain elements of the oscillograph to produce a transient linear sweep of the electron beam as well as to modulate the intensity of the electron beam during the period of the linear sweep.

The impulse generator disclosed in Fig. 4 is similar to the generator described heretofore with the exception that certain elements therein are of different characterand certain other elements have been added thereto in order to render the generator applicable for operation in connection with the oscillograph 58, as well as to illustrate changes that may be made therein when a different operating frequency is desired. With regard to the latter, inductances 36, 31 and 38 are shown as choke coils, while inductance 5B is serially connected in the discharge circuit at the low potential side of the filter network. Resistance 51 is connected between the high potendevice l8, and is bypassed by condenser 58 in order to accelerate operation of the generator. In this connection, resistance 51 has a value approximately equal to the characteristic impedance of filter network 16. Cathode 5|, of oscillograph 50, is supplied with high voltage from source 59 through resistor 66, while anode 52 and deflection plate '55 are also supplied with so characterized to maintain an opposition to hlgh Voltage from pomt 59 by way of reslstors 60 and Hi. The voltage for deflecting the electron beam of the oscillograph is applied to deflection plate 54 from the high potential side of filter network It through electrical conductor 62.

,1 The low potential side of filter network It is connected to control electrode 53', through blocking condenser 63,.while the control electrode is also connected to point 59 through resistor 64. A

resistor 65, of sufiicient value to provide the voltage. required for the extent. of intensity modulation desired, is connected in the discharge circuit of capacitance l0 between condenser 63 and ground potential.

In operation of the electrical arrangement disclosed in Fig. 4, device 18 is periodically rendered in an ionized state to periodically discharge capacitance circuit comprising inductance I15, filter network I6 and resistor 65 in a manner similar to operation of the impulse generator disclosed in Fig. 1.

At each instant device [8 becomes ionized, av

certain potential immediately appears across filter network It and resistor 65. The voltage across the filter network varies as a substantially linear function of time for the period 21r /L1C1 and then abruptly decreases to zero potential, while the voltage across resistor t5 remains substantially constant during such period of time and then abruptly diminishes to zero potential. When the voltages across the filter network and the resistor diminish, device is is abruptly deionized and discharge of capacitance IE) is terminated. Since the high voltage terminal of filter network [6 is connected to a deflection plate St, the electron beam of oscillograph 50 is linearly deflected whenever device I8 is ionized. The substantially constant voltage generated across resistor 65 is applied to control grid 53 to modulate theintensity of the electron beam during deflection thereof. A substantially linear sweep is thus produced on the viewing screen of oscillograph 59 which propagates at a high rate with great stability. This apparatus provides extremely' eificient means for indicating irregular transient voltages since the linear sweep produced on the oscillograph is extremely uniform, and furthermore, since the electron beam is simultaneously modulated with a substantially constant potential.

Another embodiment of the invention is shown in Fig. 5 of the drawings. This embodiment discloses an electrical impulse generator, embodying the novel principles included in the generators described heretofore, in combination with other means whereby extremely high voltage electrical impulses are produced. The impulse generator is so characterized that the voltage of the impulsesis a. number of times greater than the voltage applied to the generator, and that the generator is capable of producing such impulses at an extremely rapid rate. Such an impulse generator has numerous applications, especially for applying high voltage impulses for controlling operation of ultra high frequency circuits, such as anode keying, of ultra: high frequency: oscil- Il! through the discharge latorsl More particularly, the impulse generator comprises a plurality of potential storing devices which are charged with constant potential in parallel relation, with means for discharging the devices in series whereby an output voltage is obtained that is substantially greater than the input voltage by a factor equal to one-half the number of potential storing devices employed. The potential storing devices are periodically serially discharged through a discharge circuit having characteristics similar to the discharge circuits of the generators disclosed in Figs. 1 and 2 in order to maintain the discharge current substantially constant for a predetermined period of time following each instant the potential storing devices are discharged.

As shown, the impulse generator comprises a plurality of capacitances 10, H, l2, l3 and 34 which are charged in parallel relation through choke coils 15 with a constant potential applied to input terminals ii and I2. In order to serially discharge the capacitances, the high voltage terminal of capacitance ill is adapted to be connected to the low voltage terminal capacitance 1 1, while the high voltage terminals of capacitances "H, 12 and 13 are respectively adapted to be connected to the low voltage terminals of capacitances l2, l3 and 14. A discharge apparatus i6 is provided for periodically forming the foregoing connections in synchronism whereby capacitances ill, H, '12, 13 and 14 are periodically serially discharged. Apparatus '56 comprises a plurality of spark gap discharge devices Ti, l8, l9 and 88 each of which respectively include an electrode 81, 82, 83 and 8 mounted on shaft 85 which is rotated at a predetermined constant speed by motor 86. Each of the spark gap discharge devices further include a pair of electrodes which cooperate with the rotary electrodes in such a manner that an electrical connection is formed therebetween upon rotation of shaft 85. Stationary electrode 8'! of device H is connected to the high voltage terminal of capacitance 7i while the other stationary electrode 88 of the device is connected to the low voltage terminal of capacitance H, while stationary electrodes 89, Si and 93 of devices '38, i9 and 85! are respectively connected to the high voltage terminals of capacitance H, 12 and 13 and stationary electrodes 98, 92 and 94 of the latter devices are respectively connected to the low voltage terminals of capacitances l2, l3 and 14. Upon rotation of motor 86, therefore, devices J7, l3, l8 and 80 are synchronously discharged to serially connect capacitances 70, ll, i2 and 7.? and to thus apply the combined charges on the latter capacitances to capacitance M. The high voltage terminal of capacitance M is connected through inductance 95 to stationary electrode 96 of spark gap discharge device 9?. Device 9? includes electrode 98 mounted on shaft 85 for synchronous rotation with rotary electrodes 81, E32, 83 and 85. The other stationary electrode 99, of device Q! is connected to the electrical apparatus to which the output of the generator is applied. In the instant arrangement, an ultra-high frequency oscillator circuit it, including vacuum tubes Hit and I92 is disclosed with the anodes of the tubes connected to electrode 99. The low potential terminal of the oscillator is connected to low voltage input terminal 52. Rotary electrodes 8!, 82, 86 and 98 are connected to ground potential through condensers I53 in order to accelerate discharge of the spark gap devices whereby extremely rapid operation of the generator is obtained.

In order to maintain the high voltage output of spark gap device 91, that is, the voltage applied to oscillator lfifi, substantially constant for a predetermined period of time following the instant capacitances iii, H, 72, 13 and 14 are serially discharged, means are included in the serial connections between capacitances ill, H, 1'2, 73' and 14 for maintaining the discharge of the capacitances at a substantially constant rate during such predetermined period of time. Such means comprises the harmonic filter network 16 included in the generator shown in Figs. 1 and 2. In the instant arrangement, however, individual sections of the filter network are connected between the high voltage terminal of one capacitance and the low voltage terminal of the next capacitance of the series. Section 38 of filter network I6 is serially connected between capacitances 10 and "H, filter sections 30 and 3| are serially connected between capacitances l! and 72 and between capacitances l2 and 13, while filter sections 33 and 34 are serially connected between capacitances'B and M. Filter sections 33 and 34 are serially connected in a single discharge circuit between a pair of capacitances in order to illustrate the use of more than one section in such circuits. In any event, the filter sections must necessarily be connected in series in accordance with the harmonic of the fundamental frequency, the resonant frequency of section 30, to which each of the sections is tuned. Filter sections 30, 3|, 32, 33 and 34 function in a manner similar to operation of filter network Iii described heretofore to main tain an opposition to current fiow therethrough that varies as a substantially linear function of time for a period of time equal to Pin/T1, following the instant current initially flows therethrough. Also, the value of capacitances 35 are equal to one-half the series value of capacitances ill, H, l2, l3 and 14 so that the discharge current through spark gap device 91 is maintained substantially constant for the period 21r /L1cI, for reasons discussed heretofore.

Operation of the impulse generator as shown in Fig. 5 is similar to the operation of the generators described heretofore. At the instant spark gap discharge devices 11, l8, I9, and 91 form an electricalconnection between the stationary electrodes thereof, capacitances 10, ll, 12, i3 and 74 are serially discharged at a constant rate and a substantially constant potential, greater than the potential applied to terminals I! and I2, is applied across the input and output terminals of oscillator I00 for a period of time equal to 27r\/L1C1. Choke coils l5 and inductance 95 have time constants equal to ZW'VFI to prevent recharging of capacitances 70, "ll, 12, 73 and 14 until the application of constant current terminates. Motor is rotated at a speed determined by the rate of electrical impulses that are desired to be applied to oscillator I 90.

A still further embodiment of the invention is shown in Fig. 6. This embodiment discloses an electrical arrangement for impulse operation of a magnetron oscillator circuit wherein the electrical as well as the magnetic fields of the magnetron are supplied with suitable voltages from a single source. The impulse generator disclosed in Fig. 6 incorporates the novel features of the generators previously described and includes capacitances m, H, 72 and T3 which are charged in parallel relation through choke coils 15 with a source of constant potential applied to input terminals H and I2. The capacitances are periodically serially discharged through filter network IBand a magnetron'oscillator H0. Filter network I6 includes the "novel characteristics mentioned heretofore, and capacitances 35 thereof are of values equaltoone-half the series value of capacitances I0, H, I2 and 13 so that the discharge current through the filter network-and hence through magnetron oscillator I I0, remain substantially constant for the period 211'\/L1C1' following the instant capacitances are serially discharged.

As shown inthis embodiment, capacitances 10, II, I2 and I3 are serially discharged through gaseous tubes III, H2 and H3, while the charge on capacitance I3 through filter network It and magnetron oscillator H is controlled by the gaseous tube H4. The anodes of gaseous tubes III, H2 and H3 areconnected to the high voltage terminals of capacitance Ill, H and 12 respectively, while the cathodes oi the tubes are respectively connected to .the low voltage terminals of capacitances I I, I2 and I3. The cathodes of tubes III, I I2 and .I I3 are supplied with a source of synchronizing voltage from transformer I I5, through chokecoils lI6,.while the control grids .of the tubes are connected together through resistances H1. and are supplied with the output of transformer H5 through resistance H8 and through condenser H9. With the foregoing arrangement, tubesH'I, H2 and H-3 are ionized in accordance with the output of transformer II 5,,resistance H8 andcondenser I99 properly phasing thevoltage supplied to the control grids of the tubesin such amanner that the tubes are ionized when the output voltage of transformer I I5 is passing a null point. Furthermore, with this arrangement, a single source is employed for supplying the cathode voltage as well as for synchronous keying the tubes. Since the control grids of the tubes are inter-connected by way of resistances III, whenever one of the tubes is ionized'the grids of the other tubes are driven positive to render the latter tubes in an ionized state and thus obtain substantially synchronous discharge of the tubes. Condensers I20 are connected across the input and output of each of tubes III, H2 and H3 in order to accelerate ionization of the tubes and to thus further maintainsynchronous discharge thereof. Filter network I6 is serially connected between the high potential terminal of capacitance I3 and the anode of tube I I4, while magnetron oscillator I IE! is serially connected between cathode of tube I I6 and 'low'potential input terminal I2. The control grid of tube H4 is connected to the-grids of the other discharge tubes through a resistance Ill, and thecathode thereof is supplied with voltage from transformer'l I5:through choke coils H6, so that tube H4 is ionized in synchronism with ionization of tubes III, vI I2 and H3. The magnetron oscillator I Ill comprises a magnetron yoke I2I for producing the magnetic field, anodes I22 for producing electrical held and cathode I23. Magnetic yoke HI and anodes J22 are serially connected to the output of tube-I I4, while cathode I23 is connectedto low potential input terminal In operation of theimpulse generator disclosed in Fig.6, capacitances I0, 1|, I2 and I3 are charged in, parallel relation from a constant potential applied to terminals. II and I2, and are serilly discharged through filted network I5 and magnetron oscillator HII in a periodic manner controlled by synchronizing source applied to transformer H5. Whenever gaseous tubes III, H2, H3 and H4 are synchronously ionized, in

accordance with the output'oftransformer H5, capacitances I0, II and I2 are serially discharged and the combined charge on the latter capacitances are applied to capacitances I3. The increased charge on capacitance I3 is supplied through filter It to magnetron oscillator H I by way of gaseous tube H4. Due to the characteristics of filter network It and the relationship between capacitances 35 thereof and the values of capacitances I0, I I, I2 and I3, the latter capacitances are discharged at a constant rate for a period of time equal to 2m/L1C1, following the instant tubes III, H2, H3 and H4 synchronously discharge. During such period of time, therefore, substantially constant current flows through magnetic yoke I2I, anodes I22 and cathode I 23 thus applying substantially constant potential thereto for producing equal magnetic and electrical fieldsin the magnetron oscillator. Choke coils I5 and HE have time constants substantially gual to or greater than, the time interval 21r\/L1C1.to prevent charging oi capacitances I8, II, I2 and I3 during the period of constant current application, andso that tubes III, H2, H3 and H4 are abruptly de-ionized after lapse of such period.

There is thus provided by the present invention novel electrical impulse generators for producing high voltage electrical im ulses of rectangular and saw-tooth wave forms. The impulse generators are so characterized that the same are capable of operating in such a manner to produce electrical impulses at an extremely high rate whereby the same may be employed for controlling operation of ultra-high frequency electrical equipment. Moreover, the present invention provides apparatuses for effectively indicating irregular transient voltages, as well as a novel electrical arrangement for periodically applying high voltage rectangular impulses to a magnetron oscillator in such a manner that the magnetic as well as the electrical fields thereof are simultaneously produced thus allowing such oscillator to operate at high efficiency and stability.

Although'several embodiments of the invention have been described and disclosed herein, it is to be'expressly understood that various changes and substitutions may be made therein without departing from the spirit of the invention as well understood by those skilled in the art. Reference therefore will be had to the appended claims as a definition of the limits of the invention.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. In an electrical impulse generator, a condenser, means charging said condenser with a source of potential, a discharge circuit including bilateral impedance means having an opposition to current flow therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, and means discharging said condenser through said circuit, the capacity of said condenser and the value of said impedance means having a predetermined relationship to maintain substantially constant flow of current from said condenser through said circuit for said predetermined period of time following the instant said condenser is discharged 13 through said circuit, whereby said condenser discharges at a constant rate during such predetermined period of time.

2. In an electrical impulse generator, a condenser, means applying a source of constant potential to said condenser, a discharge circuit including a load impedance and capacitance means in series therewith, said discharge circuit so characterized as to ofier an opposition to flow of current therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, and means discharging said condenser through said circuit, the capacity of said condenser and the value of said capacitance means being so related that the flow of current from said condenser through said circuit remains substantially constant for said predetermined period of time following the instant said condenser is discharged through said circuit whereby said condenser dischargesat a constant rate for such predetermined period of time.

3. In an electrical impulse generator, a condenser, means applying a source of constant potential to said condenser, a discharge circuit including a load im edance and capacitance means in series therewith, said discharge circuit so characterized as to offer an opposition to flow of current therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, and means discharging said condenser through said circuit, said condenser having a capacity twice the value of said capacitance means for maintaining the current flow from said condenser through said circuit substantially constant for said predetermined period of time following the instant said condenser is discharged through said circuit whereby said condenser discharges at a constant rate for such predetermined period of time.

i. In an electrical impulse generator, a condenser, means applying a source of constant potential to said condenser, a discharge circuit including a load impedance and capacitance means in series therewith, said discharge circuit so characterized as to offer an opposition to flow of current therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current in itiall flows therethrough, and means to periodically discharge said condenser through said circuit, the capacity of said condenser and the value of said capacitance means being so related that the flow of current from said condenser through said circuit remains substantially constant for said predetermined period of time following the instant said condenser is discharged through said circuit whereby said condenser discharges at a constant rate for such predetermined period of time in a periodic manner.

5. In an electrical impulse generator, a condenser, means applying a source of constant potential to said condenser, a discharge circuit including a load impedance and capacitance means in series therewith, said discharge circuit so characterized as to offer an opposition to flow of current therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, and means responsive to an external synchronizing source for periodically discharging said condenser, said condenser having a capacity twice the value of said capacitance means for maintaining the current flow from said condenser through said circuitsubstantially constant for a predetermined period of time following the instant said condenser is discharged through said circuit whereby said condenser discharges at a constant rate for a predetermined period of time in a periodic manner determined by said synchronizing source.

6. In an electrical impulse generator, a condenser, means charging said ccndenser with a source of potential, a discharge circuit including a load impedance and capacitance means in series therewith connected to said condenser, said discharge circuit being so characterized as to offer an opposition to flow of constant current therethrough that varies substantially as a linear function of time for a predetermined period of time following the instant constant current initially iiows therethrough, an electron discharge device included in said ircuit for controlling the discharge of said condenser, and means periodically rendering said device conducting for pcriodically discharging said condenser through said circuit, the capacity of said condenser and the value of said capacitance means being so related that the flow of current from said condenser through said circuit remains substantially constant for said predetermined period of time following each instant said condenser is discharged through said circuit whereby said condenser discharges at a constant rate for such predetermined period of time in a periodic manner.

7. In an electrical impulse generator, a condenser, a charging circuit for applying a constant potential to said condenser, a discharge circuit including capacitance means connected to said condenser, said discharge circuit being so characterized as to oifer an opposition to flow of constant current therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, an electron discharge device included in said circuit for controlling the discharge of said condenser, means periodically rendering said device conducting for periodically discharging said condenser through said circuit, the capacity of said condenser and the value of said capacitance means being so related that the flow of current from said condenser through said circuit remains substantially constant for said predetermined period of time following the instant said condenser is discharged through said circuit, means rendering said device non-conducting after lapse of said predetermined period of time, and time delay means included in said charging circuit for preventing application of constant potential to said condenser during said predetermined period of time.

8. In an electrical impulse generator, a condenser, means applying a source of constant potential to said condenser, a discharge circuit connected to said condenser, said discharge circuit including a series of capacitance and inductance combinations so characterized as to offer an opposition to flow of current therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, and means discharging said condenser through said circuit, the capacity of said condenser and the value of said capacitance means being so related that the flow of current from said condenser through said circuit remains substantially constant for said predetermined period of time following the instant said condenser is discharged through said circuit whereby said condenser dis- 15 charges ata constant rate for such predetermined periodoi time.

9. In an'electrical impulse generator, a condenser, means applying a source of constant potential to said condenser, a discharge circuit connectedto said condenser, said discharge circuit including a plurality of capacitance and inductance combinations tuned to different irequenciesand connected in harmonic relation to offer an opposition to current flow therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, and means discharging said condenser through said circuit, the capacity of said condenserand the value of said capacitance means havingapredetermined relationship to establish a substantially constant flow of current from said condenser through said circuit for said predetermined period of time following the instant said condenser is discharged through said circuit whereby said condenser discharges at a constant rate ior such predetermined period of time.

10. In an electrical impulse generator, a condenser, means charging said condenser with a source of constant potential, a discharge circuit connected to said condenser, said discharge circuit including a filter network having capacitance means and being so characterized to maintain an opposition to the flow of current therethrough that varies as'a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, means discharging said condenser through said circuit, and said condenser having a capacity twice the value of said capacitance means for maintaining the current flow from said condenser through said circuit substantially constant for said predetermined period of time following the instant said condenser is discharged through said circuit whereby the voltage generated across said filter varies as a substantially linear function of time during such predetermined period of time.

11. In an electrical impulse generator, a condenser, means charging said condenser with a source of constant potential, a discharge'circuit connected to said condenser, said discharge circuit including a filter network having a plurality of parallel connected cap'acitances and inductances tuned to difierent frequencies and serially connected in harmonic'relat-ion to maintain an opposition to the flow of current therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, means discharging said condenser through said circuit, and said condenser having a capacity twice the value of said capacitance means for maintaining the current flow from said condenser through said circuit substantially constant for said predetermined period of time following the instant said condenser is discharged throughsaid circuit whereby the voltage generated across said filter varies as a substantially linear function of time during such predetermined period of time.

12. In an electrical impulse generator, a condenser, means applying a source of potential to said condenser, a discharge circuit including a filter network and an impedance, said filter network including capacitance means and so characterized as to offer an opposition to the flow mined period or time following the instant current initially flows therethrough, means periodically discharging said condenser through said circuit, the capacity of said condenser and the value of said capacitance means being so related that the flow of current from said condenser through said circuit remains substantially constant for said predetermined period of time following the instant said condenser is discharged through said circuit whereby a substantially linearly varying voltage is generated across said filter and a substantially constant potential is generated across said impedance during said predetermined period of time.

13. In an electrical impulse generator, a condenser, means oharging said condenser with a source of constant potential, a discharge circuit connected to said condenser, means discharging said condenser through said circuit, and bilateral impedance means included in said circuit for maintaining an opposition to current flow therethrough that varies as a substantially linear function or time for a predetermined period of time following the instant current initially flows therethrough, the last-named means having a predetermined relationship with the capacity of said condenser to maintain substantially constant current flow from said condenser through said circuit for said predetermined period of time.

14. In an electrical impulse generator, a plurality of condensers, means charging said condensers in parallel relation with a source of constant potential, a discharge circuit including a load impedance and impedance means in series therewith to maintain an opposition to current flow therethrough that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, and means serially discharging said condensers through said discharge circuit, the capacities of said condensers and the value of said impedance means having a predetermined relationship to maintain substantially constant flow of current from said condensers through said circuit for said predetermined period of time.

15. In an electrical impulse generator, a plurality of condensers, means charging said condensers in parallel relation with a source of constant potential, a load impedance, and a discharge circuit for serially discharging said condensers through said load impedance, said discharge circuit including impedance means in series with the load impedance to maintain an opposition to current flow through said circuit that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, the capacities of said condensers and the value of said impedance means having a predetermined relationship to maintain substantially constant flow of current from said condensers through said circuit for said predetermined period of time following the instant said condensers are serially discharged through said circuit whereby a substantially constant potential, greater than said constant potential, is maintained across said load impedance for said predetermined period of time. 7

16. In an electrical impulse generator, a plurality of condensers, means charging said condensers in parallel relation with a source of constantpotential, an impedance, a discharge circuit including impedance means for serially dischargingzsaid condensers through said impedance, said impedance means including a plurality of capacitance and inductance combinations to maintain an opposition to current flow through said circuit that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, the capacities of said condensers and the value of said impedance mean having a predetermined relationship to maintain substantially constant flow of current from said condensers through said circuit for said predetermined period of time following the instant said condensers are serially discharged through said circuit whereby a substantially constant potential, greater than said constant potential, is maintained across said impedance for said predetermined period of time.

17. In an electrical impulse generator, a plurality of condensers, means charging said condensers in parallel relation with a source of constant potential, an impedance, a discharge circuit including impedance means for serially discharging said condensers through said impedance, said impedance means including a plurality of capacitance and inductance combinations tuned to different frequencies and serially connected in harmonic relationship to maintain an opposition to current flow through said circuit that varies as a substantially linear function of time for a predetermined period of time following the instant current initially flows therethrough, the capacities of said condensers and the value of said impedance means being so related that the flow of current from said condensers through said circuit remain substantially constant for said predetermined period of time following the instant said condensers are serially discharged through said circuit whereby a substantially constant potential, greater than said constant potential, is maintained across said impedance for said predetermined period of time.

18. In an impulse generator, a plurality of condensers, means charging said condensers in parallel relation from a source of constant potential, and means discharging said condensers through an impedance to maintain a substantially constant potential across said impedance for a predetermined period of time, the lastnamed means including means for synchronously forming electrical connections between said condensers to synchronously discharge said condensers in series, impedance means included in series in each of said connections, each of said impedance means having a predetermined relationship with the impedance means included in the other connections to maintain an opposition to current flow through said serially connected condensers that varies as a substantially linear function of time for a predetermined period of time following the instant said condensers are serially discharged, and the value of said impedance means having a predetermined relationship with the capacities of said condensers to maintain the discharge of said condensers at a constant rate for such predetermined period of time.

19. In an impulse generator, a plurality of condensers, means charging said condensers in parallel relation with a source of constant potential, and means discharging said condensers through an impedance in such a manner as to maintain a substantially constant potential across said impedance for a predetermined period of time, the last-named means including means for synchronously forming electrical connections between said condensers in such a manner as to synchronously discharge said condensers in series, impedance means included in each of said connections, each of said impedance means comprising inductance and capacitance combinations tuned to different frequencies and so related to the other impedance means to maintain an opposition to current flow through said serially connected condensers that varies as a substantially linear function of time for a predetermined period of time following the instant said condensers are serially discharged, and the value of said impedance means being so related to the capacities of said condensers to maintain the discharge of said condensers at a constant rate for such predetermined period of time.

20. In combination with an oscillator circuit, a plurality of condensers, means charging said condensers in parallel relation with a source of constant potential, and means discharging said condensers through said oscillator circuit to maintain a substantially constant potential across said circuit for a predetermined period of time, the last-named means including means for synchronously forming electrical connections between said condensers to synchronously discharge said condensers in series, impedance means included in series in each of said connections, each of said impedance means having a predetermined relationship to the impedance means included in the other connections to maintain an opposition to current flow through said serially connected condensers that varies as a substantially linear function of time for a predetermined period of time following the instant said condensers are serially discharged, and the value of said impedance means having a predetermined relationship to the capacities of said condensers to maintain the discharge of said condensers at a constant rate for such predetermined period of time.

21. An impulse generator comprising charge storage means, a load impedance and, means for discharging the charge storage means through the load impedance including in series a circuit having a resonant period twice the discharge time.

22. An impulse generator comprising charge storage means, a load impedance, and means for discharging the charge storage means through the load impedance, including in series a plurality of inductance-capacity networks resonant at diiferent frequencies.

23. An impulse generator comprising charge storage means, a load impedance, and means for discharging the charge storage means through the load impedance including in series a plurality of inductance-capacity networks resonant at frequencies substantially harmonically related.

24. An impulse generator comprising charge storage means, a load impedance and means for discharging the stored charge through the load impedance comprising resonant circuit means transiently operative under shock excitation to control the discharge current during the discharge period.

25. An intermittent high frequency wave group generating system havin a vacuum tube oscillator and a power supply circuit therefor comprising a charge storing circuit, means charging the charge storing circuit with a constant potential, and means periodically connecting the storage circuit to the vacuum tube oscillator comprising a rotary spark gap.

26. An electrical impulse generatori'comprising a circuit having a plurality of condensers connected in p rallel, means includinga plurality 1 of spark gaps each disposed in seriesv connection withrespect to said condensers, means to supply energy to said condensers, means to control breakdown of said gaps to effect discharge of the ener y stor d in said ondensers in, series add v relation through said gaps to, produce a large discharge impulse, an output load resistance, an --,i nductanc e coil in, series between, said spark gaps and said output, load resistance to control the rise-to-decay time ratio of the produced impulse. 27. The generatordefined in claim 26 wherein the gap breakdown control means comprises means to con r l. the spacin f he aps.-

28. A system for generating regularly repetitive high voltage electrical pulses comprising a plurality of condensers and discharge devices connected alternately in series, means for charging thev condensers to a voltage below the breakdown voltage of said discharge devices including a source of charging energy connected to said condensers in parallel, a, source of low voltage electrical triggering pulses, a vacuum tube comprising a cathode, a control grid and an I 30. An electrical impulse generator comprising. a circuit having a plurality of energy storage 29 means connected in parallel, means including a plurality of voltage discharge means each disposed in series connection with respect to'said energy storage means, means to supply energy to said energy storage means, means to control breakdown of said voltage discharge means to efiect dischargeof the energy stored in said voltage storage means in series additive relation through said voltage discharge means to produce a large discharge impulse, a load impedance, and inductance means in series between said voltage discharge means and said load impedance to control the rise-to-decay time ratio of the produced impulse.

ARTHUR A. VARELA.

REFERENCES CITED UNITED STATES PATENTS Number Name Date. r

1,613,954 Knoop Jan. 11, 1927 2,114,938 Puckle Apr. 19, 1938 2,118,352 Lewis May 24, 1938 2,130,132 Hollmann Sept. 13, 1938 2,149,077 Vance Feb. 28, 1939 2,297,529 Andrieu July 9, 1940 2,213,843 Kolbskofi Sept. 3, 1940 2,221,573 Bruckmann Nov. 12, 1940 2,294,863 I-Iadfield Sept. 1, 1942 2,299,571 Dome Oct. 20, 1942 2,411,140 Lindenblad Nov. 12, 1946 7 2,418,128 Labin et a1. Apr. 1, 1947 2,419,574 Lehmann Apr. 29, 1947 

